Diaphragm for sound recording, reproducing, and transmitting instruments.



No. 648,975. Patented May 8, i900. E. H. MORLEY.

DIAPHRAGM FOR SOUND RECORDING, REPRODUCING, AND TRANSMITTING INSTRUMENTS(Application filed Jan, 8, 1899.)

(No Model.)

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UNITED STATES PATENT OFFICE.

EDWIN n. MORLEY, on PHILADELPHIA,'PENnsYLvAniA.

DIAPHRAGM FOR SOUND RECORDING, REPRODUCING, AND TRANSMITTINGINSTRUMENTS.

srncmroarxou forming part of Letters meant no. 648,975,, dated May a,190 Application filed June 8, 1899. Serial No- 719,762. (No model.)

Be it known that I, EDWIN II. MOBLEY, of the city and county ofPhiladelphia, State of Pennsylvania, have invented an Improvement inDiaphragms for Sound Recording, Reproducing, and TransmittingInstruments, of which the following is a specification.

My invention relates to diapliragms for sound recording, reproducing,and transmitting instruments; and it consists of the improvements whichare fully set forth in the following specification and are shown in theaccompanying drawings.

Many efforts have been made to improve the tone, volume, and quality ofsounds trans mitted by sound recording, reproducing, and transmittinginstruments, and these efforts have been chiefly directed toward theimprovement of the diaphragms, through the vibrations of which thesound-waves are transmitted. In most of the diaphragms used much of thesound is lost by the transmission of a part of the vibrations laterallythrough the'diaphragm to the head or frame by which To all 7071 0122 itmay concern:

the diaphragm is carried, which has the elfectnot only of decreasing theeffective vibrations, but also of imparting an artificial tone or timbreto the transmitted sounds by the vibrations of the substance of the heador frame. To overcome this difiiculty, it has been proposed to form thecentral and outer portions of the. diaphragm of distinct pieces unitedby strips between the central and outer portions. In such cases theopenings formed in the diaphragm permit a portion of the sound-waves topass through the openings w-thout acting upon the diaphragm. Suchsound-waves are lost and the passage of the air-cu r'rents through theseopenings tends to affect the sound-waves produced by the vibrations ofthe central portion of the diaphragm. It has also been proposed to formthe central and outer portions of the diaphragm of separate piecesconnected by an annulus or ring; but in such case the connecting annulusor ring has impeded rather than increased the vibration of the centralplate and has not efFeetively prevented the lateral transmission ofvibrations to the outer portion and thencct-o the frame or head.

It is the objectof' this invention to obtain the maximum effect ofthevibration of the diaphragmwith a minimum dissipation or parted andthe outer edge by which the'diaphragm is clamped or secured in theframe.

. "In the accompanying drawings, Figure l is a vertical sectional viewof a reproducerhead of a phonograph employing my improved diaphragm.Fig. 2 is a similar view of the reproducerhead of a graphophone. Fig. 3is a plan view of the diaphragm. Fig. 4 is a cross-sectional view of oneform thereof. Fig. 5 is a similar view of another form-and Fig. 6 is across-sectional view of a diaphragm embodying my invention andillustrating an additional feature thereof.

My improved diaphragm maybe used in any sound recording and reproducinginstrument.' For purposes of illustration I have shown it applied to thereproducingheads of a phonograph and graphophone. It may also beemployed in gramophones and in the re cording as well as in thereproducing heads and may be used in telephonic apparatus.

My invention is not concerned with the construction of the soundrecording and reproducing instruments, and as the phonograph and'graphophone reproducers shown are of well-known construction they willnot be particularly described. A is a diaphragm, which may be composedof a thin disk or plate of any suitable material, whether metallic,vegetable,-or animal. I prefer, however, to employ metal, and haveobtalined most excellent results with forgedstee tral portion a and anouter portion Z), surrounding the central portion and united therewithby a continuous and relatively-attenuated narrow part c... In mypreferred construction the diaphragm may be produced by This-diaphragmis composed of a censurface, forming the attenuated portion a and arelatively-thick central portion a and outer inclosing portion Z), andthis groove may be made upon one surface only, as shown in Fig. 4, orupon both surfaces, as shown in Fig. 5.

It will be understood that the thickness of the diaphragms shown in thedrawings, and particularly in Figs. 4 and 5, is greatly exaggerated forpurposes of illustration. In practice the diaphragm is a very thinsheet; but the central portion a and the outer inclosing portion 1) arerelatively of substantially greater thickness than the connectingportion 0. I find that the sound may be niaterially improved by makingthe front face of theldiaphragm convex or by making the central portiona. concavo-convex, as shown in Fig. (3-. It is not necessary that theouter portion I) should be of the same thickness as the inner centralportion a. It may, if desired, be made heavier or thicker to form a moreeffective means of clamping the diaphragm in place. The diaphragm isclamped or secured in the head in the usual manner by the outer portion3), as by a clamping-ring B between Washers d. The shank C of thestylus, needle, or point is connected with the central portion a in theusual manner. The advantages of this construction are that theattenuated connecting portion 0 by reason of its relatively-greaterthinness permits a much greater resilience in the central 9r operativeportion of the diaphragm, so that that portion is much more sensitive tothe soundvvaves and more accurately transmits the vibrat-ions; also,that the vibrations of the central portion of the diaphragm are nottrans mitted laterally to so great an extent through the attenuatedportion 0 to the outer portion 1), and are consequently not dissipatedor lost, and also that as the diaphragmis closed throughout and notprovided with any openings or perforations thereis consequently nopassage of air currents or waves directly through it which would resultin a loss of part of the ciicctive vibrations and also objectionablyaffect those transmitted through the plate.

What I claim as new, and desire to secure by Letters Patent, is asfollows;

1. A diaphragm for sound recording, rcproducingand transmittinginstruments, con sisting of a thin plate or disk having its centralportion connected with the outer portion or edge by a relatively. thinor attenuated connecting part, said central portion and outer portionbeing of greater thickness than said connecting portion.

2. A diaphragm for sound recording, rcproducing andtransmittinginstruments, consisting of a thin plate or disk having itscentral portion connected with the outer portion or edge by arelativelythin or attenuated connecting part said diaphragm beingcomposed of a single integral piece.

3. A diaphragm for sound recording, ro producing and transmittinginstruments consisting of a thin plate or disk having a continuousgrooveadjaccnttoits outer-edge forming a relatively thin or attenuated portion0 between the relatively-thick central portion and outer edge.

4. A diaphragm for sound recording, rcproducing or transmittinginstruments coir sisting of a thin plate or disk having its centralportion provided with a convex front face and connected with the outerportion or edge bya relatively thin orattenuated connecting part.

5. A diaphragm for sound recording, re-

producing or transmitting instruments, con;

sisting of a thin plate or disk, having a concavo-convex central portionconnected with the outer port-ion or edge by a relatively thin orattenuated connecting part.

In testimony of which invention l have hereunto set my hand.

EDWIN ll. MORLEY.

W itncsscs:

Ensns'r Ilownno Hux'rnn, J. W. Knuwon'rnv.

